Add composer support for plugins

app/Providers/PluginServiceProvider.php

@@ -38,6 +38,11 @@ class PluginServiceProvider extends ServiceProvider
         $this->registerPluginCallbackListener();
         $this->registerClassAutoloader($src_paths);
 
+        // Register plugin's own composer autoloader
+        foreach ($plugins->getEnabledComposerAutoloaders() as $autoloader) {
+            require $autoloader;
+        }
+
         $bootstrappers = $plugins->getEnabledBootstrappers();
 
         foreach ($bootstrappers as $file) {

app/Services/PluginManager.php

@@ -219,6 +219,24 @@ class PluginManager
         return $bootstrappers;
     }
 
+    /**
+     * Loads composer autoloader for the enabled plugins if exists.
+     *
+     * @return Collection
+     */
+    public function getEnabledComposerAutoloaders()
+    {
+        $autoloaders = new Collection;
+
+        foreach ($this->getEnabledPlugins() as $plugin) {
+            if ($this->filesystem->exists($file = $plugin->getPath().'/vendor/autoload.php')) {
+                $autoloaders->push($file);
+            }
+        }
+
+        return $autoloaders;
+    }
+
     /**
      * The id's of the enabled plugins.
      *